This invention relates to a fuel cell having such a structure that a gaseous fuel and a gaseous oxidizing agent are fed to the anode and the cathode, respectively, of a pair of gas-diffusible electrodes counterposed on both sides of a liquid electrolyte, and particularly to a fuel cell using phosphoric acid as an electrolyte.
The fuel cell having such a structure that a gaseous fuel is fed to the anode of the electrodes counterposed on both sides of a liquid electrolyte and a gaseous oxidizing agent to the cathode includes, for example, a fuel cell using phosphoric acid as an electrolyte and a fuel cell using fused carbonate as an electrolyte.
It is known that the performances of these fuel cells are lowered with an increase in the operating time. To prevent the fuel cell performance from the lowering, various studies and improvements of electrodes or electrolyte-retaining matrices have been made. For example, Japanese Patent Publication No. 58-156 corresponding to U.S. Pat. No. 4,017,664 discloses an electrolyte-retaining matrix made from silicon carbide particles and a binder in the so called phosphoric acid type fuel cell using phosphoric acid as an electrolyte, where the silicon carbide particles have particle sizes of less than 25 .mu.m, preferably 10 .mu.m. Japanese Patent Publication No. 47-10135 corresponding to U.S. patent application Ser. No. 435,827 filed on Mar. 1, 1965 now U.S. Pat. No. 4,419,493 and Japanese Patent Application Kokai (Laid-Open) No. 51-86734 corresponding to U.S. patent application Ser. No. 533,918 filed on Dec. 18, 1974 now abandoned disclose processes for preparing an electrode for a phosphoric acid type fuel cell, with no regard to any distiction between the cathode and the anode.
On the other hand, U.S. Pat. No. 4,017,663 discloses electrodes in which the amount of polytetrofluoroethylene as a water-repellent binder in an anode is different from that in a cathode, but no disclosure is made at all of the firing temperature of electrodes and the phosphoric acid saturated absorption amounts of electrodes.